Method of fire protection using recirculation of combustion products to discharge a foam extinguishant

ABSTRACT

A method of fire protection in which a foam extinguishant is discharged towards the fire in response to a predetermined fire condition in the space to be protected. At least a portion of the foam discharge is terminated and a fluid extinguishant is discharged towards the fire in response to an additional predetermined fire condition.

METHOD OF FIRE PROTECTION USING RECIRCULATION OF COMBUSTION PRODUCTS TO DISCHARGE A FOAM EXTINGUISHANT CROSS-REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION This invention relates to a method for fire protection, and more particularly to such a method which utilizes the products of combustion from a fire to aid in extinguishing the fire.

In the above-mentioned related application Ser. No. 131,988, a fixed fire extinguishing system is disclosed in which the combustion products of a fire developing in the enclosure to be protected are circulated back towards the fire at the early stage" of the fire development to prevent the ingress of air to the fire. The circulation of the combustion products is achieved by the use of a plurality of aspiration-type nozzles which are mounted near the ceiling of the enclosure, with each It is a further object of the present invention to provide a method for fighting a fire in which at least a portion of the discharge of foam extinguishant is replaced by a discharge of fluid extinguishant in response to the additional information received from the fire.

Towards the fulfillment of these and other objectsof the present invention, the method of the present invention comprises the steps of discharging a foam extin guishant towards the fire in response to. a predetermined fire condition in the space to be protected, changing said discharge in response to an additional predetermined fire condition in said space, and discharging a fluid extinguishant towards said fire in response to said additional predetermined fire condition.

BRIEF DESCRIPTION OF THEIDRAwINos Reference is now made to the accompanying drawingsfor a better understanding of the nature and objects of the present invention. The drawingsillustrate having an inlet opening for receiving the products of 3 5 combustion and a discharge opening for discharging the products of combustion. When actuated, the nozzles discharge an extinguishant towards the fire which creates an aspiration effect and circulates the products of combustion in a path upwardly from the fire, through the nozzles, and downwardly into the fire. In this manner, air entering the building through its windows and doors and passing towards the fire is blocked by the barrier created by theproducts of combustion.

I Although the above arrangement was found to be ef- I fective in extinguishing fires, it suffered. fromthe fact that the extinguishant discharge velocity from the nozzles had to be set at arelatively high value in order to obtain the aspiration effect. Since thiswas accomplished by utilizing a relatively small discharge opening,

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method of the above type in whichthe combustion products from the fire are circulated in a path including said fire, with the circulation aiding in producing a foam extinguishant and being reduced or terminated in response to additional information received from the fire.

the best mode presently contemplated forcarrying out the objects of the invention and are not to be construed as, restrictions or limitations on its scope. In the draw- Ings: I I

FIG. 1 is a vertical cross-sectional view of the-discharge device of the present invention; I

'FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1; and I p FIG. 3 is a view similar to FIG. 1,- but showing theldevice of the present invention after responding to a fire condition. i

1 DESCRIPTION OF THE PREFERRED j EMBODIMENTS A dischargedevice for carrying out the method of the present invention is depicted in FIG. 1 of the drawings and includes a nozzle unit 10 defining a discharge outlet l0a at its lower end as viewed in FIG. 1 and having a T-shaped coupling member 12 threadably connected to its upper end. One end portion of the coupling member 12 is internally threaded as shown at 12a for connection to a branch line 13 for supplying an extinguishant such as water, it being understood that a typical fire protection system will include several discharge devices and branch lines, along with submains, risers, and a main, to supply the branch lines with" an extinguishant, such as a mixture of water and a foaming compound, in a conventional manner, and as shown and described in the above-mentioned related application.

A closure plug 14 is threadably engaged in the other .end portion 12b of the coupling member 12 and defines a central opening which receives a valve stem 16 slidablyextending therethrough. Avalve head 18 is connected to one end of the valve stem 16 and is adapted to engage a cooperating seat 20 supported by the internal wallof the coupling member 12 toblock the flow of extinguishant through the coupling member.

A lever arm 22 is pivotally mounted to the plug 14 and is adapted to be connected, by means of afusible link 24, toa lever arm 26 fixed with respect to the plug. The pivotal lever arm 22 has a projection engaging the other end of the valve stem 16 to maintain the valve head 18 against the seat 20 as long as the fusible link 24 maintains the connection between the levers 22 and 26. I v v A pair of vanes, shown in general by the reference numeral 32, are provided in the interior of the nozzle unit in order to impart a swirling-type motion to the extinguishant as it passes through the nozzle unit, thereby resulting in a continuous conical spray discharge from the discharge outlet 10a, in a conventional manner.

A circumferential groove 34 is formed in the outer periphery of the nozzle unit 10 for reasons that will be explained in detail later.

An open-ended, hollow housing 40, formed in the shape of a venturi, extends over the bottom portion of the nozzle unit 10 and has an inlet 40a and an outlet 40b for respectively receiving and discharging the products of combustion from the fire. An extension 42 for the discharge opening 10a is mounted relative to the housing 40 by means of a plurality of struts 44, two of which are shown in FIG. 1. The extension 42 extends over the discharge end portion of the nozzle unit 10 and has a discharge opening 42a which registers with the discharge outlet 100, with the opening 42a being of a smaller diameter than the outlet 10a. in an exemplary embodiment of the present invention, the outlet 10a would have a diameter of approximately one-half inch and would discharge the extinguishant at a spray angle of approximately 150", while the opening 42a would have a diameter of approximately one-eighth of an inch and would discharge the extinguishant at a spray angle of approximately 100. v

The housing 40 is connected relative to the nozzle unit 10 by meansof three substantially L-shaped connecting arms 50. Each of the arms 50 consists of a lower portion 50a which engages underneath an inwardly-directed circular flange 400 formed on the upper end of the housing 40, and an upper portion 50b which engages a split ring 52 extending around the upper end portion of the nozzle unit 10 and having its ends normally connected by a fusible link 54. The elbow portionsof the arms 50 are supported by, and extend within, the circumferential groove 34.

Referring specifically to FIGS. 1 and 2 for a better view of the interconnection between the upper arm portions 50b and the ring 52, it is seen that the arm portions are curved slightly at their upper ends so that they extend around, and over, the top surface of the ring. In this manner the ring 52 can be designed to maintain the arms 50 under a slight, inwardly directed spring tension in order to maintain the arms, and therefore the housing 40, in the position shown in FIG. 1. Of course, when the link 54 fuses in response to a predetermined temperature, the ends of the ring are free to separate,- which will release the arms 50 and therefore permit the housing 40 to fall, from thenozzle 10 under the force of gravity.

The temperatures required to fuse the fusible link 24 and the fusible link 54 may vary in accordance with particular design considerations. A preferred embodiment would have the fusible link 54 adapted to fuseat a temperature greater than the fusible link 24, with a specific example of the fusing temperatures being 165F. for the link 24 and 500F. for the link 54.

As an example of the operation of the discharge device and using a mixture of water and a foaming compound as the extinguishant,-upon the temperature in the vicinity of the fusible link 24 reaching 165F.', the link will collapse and permit a pivoting of the arm 22 relative to the arm 26 under'the force of the valve stem 16 as a result of the extinguishant pressure acting against the valve head 18. This permits the valve head 18 to unseat from the seat 20 and extinguishant to flow into and through the nozzle unit 10. The resulting discharge of the extinguishant from the device will be at a relatively high velocity, a relatively low rate, and a relatively narrow spray angle due to the presence of the relatively small discharge opening 42a provided by the extension 42. This relatively high velocity is sufficient to induce the products of combustion from the fire to enter the housing 40 through its inlet 40a.This, plus the venturi shape of the housing 40, creates an aspiration effect which circulates the products of combustion from the fire in a path upward from the fire, downwardly through the inlet 40a, and outwardly from the housing through the outlet 40b. The products of combustion thus mix with the extinguishant in the housing 40 and cause the foaming compound to foam, with the compound preferably being such that the resulting foam would consist of between ZOO-1,000 parts combustion products to 1 part of water by volume. As a result, the products of combustion will be encapsuled in the foam bubbles and will be circulated downwardly into the fire in the above manner. As emphasized in the above-cited application, in addition to the discharge of foam, this circulation of the combustion products creates a barrier which prevents air entering the building through doors, windows, etc., from passingdirectly into the fire. As a result, the fire will be smothered and rendered relatively easy to extinguish. I

In the event the above circulation of combustion products by means of the foam does not completely extinguish the fire, and assuming the fire causes the temperature in the vicinity of the device to increase to approximately 500F., the fusible link 54 will collapse, permitting a release of the split ends of the ring 52 and a release of the arms from the ring. The housing 40 will thus be released from the position shown in FIG. 1 and will fall away from the nozzle unit 10'. As a result, the device will take the operational position shown in FIG. 3, with the extinguishant flowing directly into the nozzle unit 10 and being directly discharged'to the fire in a fluid state from the relatively large outlet 10a at a relatively high rate and at a relatively wide angle spray of droplets. Thus, in the latter operational mode of the device, the above-mentioned aspiration effect willbe eliminated and the rate of extinguishant discharge and the area of coverage will be increased.

In a system incorporating several of the discharge devices, it is apparent that, in a typical high-challenge fire situation, the initial discharge of foam will be reduced as a result of the discharge devices directly over the tire attaining their direct discharge mode while the peripheral devices will continue to discharge foam andcirculate the combustion products in the above manner. As a result the former devices will have a relatively good chance of extinguishing the fire directlysince the latter devices will prevent the ingress of air to the fire. As a According to a feature of the present invention, any water based foamforming fluid may be used in accordance with the foregoing. It can be a mixture of water and a foaming compound such as any one of a number of synthetic surface active agents that are stable with the fire products of combustion. The foaming compound could be injected into the waterline in response to a fire situation and the resulting fluid will be discharged through the outlet 42a in accordance with the foregoing.

Other examples of extinguishants that may be used in the present invention are water and gaseous agents such as pressurized nitrogen, carbon dioxide, halogenated hydrocarbon agents such as freon, or other similar gases, as discussed in detail in the above-mentioned application.

It is understood that several other variations may be made in the foregoing without departing from the scope of the invention. For example, the detector sys tern disclosed in the above-mentioned related application and adapted to reduce the rate of discharge provided to each nozzle after a predetermined time delay, can be used in the method of the present invention. Also, the sizes of the outlet a and the opening 42a, as well as the fusing temperatures for the links 24 and 54, may be varied in accordance with the present invention.

Still other variations of the specific construction and arrangement of the method disclosed above can be made by those skilled in the art without'departing from the invention as defined in the appended claims.

I claim:

1. A method of fighting a fire comprising the steps of discharging a foam extinguishant towards the fire in re sponse to a predetermined fire condition in the space to be protected, terminating said discharge in response to an additional predetermined fire condition in said space, and discharging a fluid extinguishant towards said fire in response to said additional predetermined fire condition. y

2. The method of claim 1 wherein the discharge of said fluid extinguishant is at a greater rate than the discharge of said foam extinguishant.

3. A method of fighting a fire comprising the steps of discharging a foam extinguishant from a plurality of sources towards the fire in response to a predetermined fire condition in the space to be protected, terminating said discharge from at least a portion of said sources in response to an additional predetermined fire condition in said space, and discharging a fluid extinguishant from said portion of sources towards said fire in response to said additional predetermined fire condition.

4. The methodof claim 1 wherein the discharge of said fluid extinguishant isat a greater rate than the discharge of said foam extinguishant.

5. The method of claim 1 wherein said step of discharging a foam extinguishant is done in response to a predetermined temperature in said space and wherein said steps of terminating and discharging afluid extinguishant is done in response to a temperature insaid space greater than said predetermined temperature.

6. The method of claim 1 wherein said fluid extinguishant is a foam formingfluid and wherein said step of discharging a foam extinguishant comprises the step of discharging said foam forming fluid.

7. The method of claim 6 further comprising the step of circulating the combustion products from said fire in a path including said fire in response to said first predetermined fire condition to cause the foaming of said fluid.

8. The method of claim 7 wherein said step of discharging a fluid extinguishant includes the step of -terminating said circulation of combustion products to terminate the foaming of said fluid.

9. The method of claim 8 further comprising the step of increasing said discharge of fluid extinguishant in response to said step of terminating.

10. The method of claim 3 wherein said step of discharging a foam extinguishant is done in response to a predetermined temperature in said space and wherein said steps of terminating and discharging a fluid extinguishant is done in response to a temperature in'said space greater than said predetermined temperature.

11. The method of claim 3 wherein said fluid extinguishant is a foam forming fluid and wherein said step of discharging a foam extinguishant comprises the step of discharging said foam forming fluid.

12. The method of claim 11 further comprising the step of circulating the combustion products from said fire in a path including said fire in response to said first predetermined fire condition to cause the foaming of said fluid.

'13. The method of claim 12 wherein said step of discharging a fluid extinguishant includes the step of ter minating said circulation of combustion products to terminate the foaming of said fluid.

14. The method of claim 13 further comprising the step of increasing said discharge of fluid extinguishant in response to saidstep of terminating. 

1. A method of fighting a fire comprising the steps of discharging a foam extinguishant towards the fire in response to a predetermined fire condition in the space to be protected, terminating said discharge in response to an additional predetermined fire condition in said space, and discharging a fLuid extinguishant towards said fire in response to said additional predetermined fire condition.
 2. The method of claim 1 wherein the discharge of said fluid extinguishant is at a greater rate than the discharge of said foam extinguishant.
 3. A method of fighting a fire comprising the steps of discharging a foam extinguishant from a plurality of sources towards the fire in response to a predetermined fire condition in the space to be protected, terminating said discharge from at least a portion of said sources in response to an additional predetermined fire condition in said space, and discharging a fluid extinguishant from said portion of sources towards said fire in response to said additional predetermined fire condition.
 4. The method of claim 1 wherein the discharge of said fluid extinguishant is at a greater rate than the discharge of said foam extinguishant.
 5. The method of claim 1 wherein said step of discharging a foam extinguishant is done in response to a predetermined temperature in said space and wherein said steps of terminating and discharging a fluid extinguishant is done in response to a temperature in said space greater than said predetermined temperature.
 6. The method of claim 1 wherein said fluid extinguishant is a foam forming fluid and wherein said step of discharging a foam extinguishant comprises the step of discharging said foam forming fluid.
 7. The method of claim 6 further comprising the step of circulating the combustion products from said fire in a path including said fire in response to said first predetermined fire condition to cause the foaming of said fluid.
 8. The method of claim 7 wherein said step of discharging a fluid extinguishant includes the step of terminating said circulation of combustion products to terminate the foaming of said fluid.
 9. The method of claim 8 further comprising the step of increasing said discharge of fluid extinguishant in response to said step of terminating.
 10. The method of claim 3 wherein said step of discharging a foam extinguishant is done in response to a predetermined temperature in said space and wherein said steps of terminating and discharging a fluid extinguishant is done in response to a temperature in said space greater than said predetermined temperature.
 11. The method of claim 3 wherein said fluid extinguishant is a foam forming fluid and wherein said step of discharging a foam extinguishant comprises the step of discharging said foam forming fluid.
 12. The method of claim 11 further comprising the step of circulating the combustion products from said fire in a path including said fire in response to said first predetermined fire condition to cause the foaming of said fluid.
 13. The method of claim 12 wherein said step of discharging a fluid extinguishant includes the step of terminating said circulation of combustion products to terminate the foaming of said fluid.
 14. The method of claim 13 further comprising the step of increasing said discharge of fluid extinguishant in response to said step of terminating. 